We are changing Vengeance to increase AP equal to 5% of the damage you take for 20 sec. This buff will "roll" so that as it gets refreshed the unused part is added to the new buff, similar to how Ignite or Stagger work. The net result will be that Vengeance stacks by the amount of DPS being thrown at you over 20 sec. There is no cap.

Something's going on with the EF data though. There's a distinct difference in the scaling for the three higher-AP data sets. I'm not sure what's going on, but the SP scaling for those last three data points is about 10% higher than the first three.

In any event, we're expecting something like (4030-4491)+0.377*SP for the base heal, and getting closer to 0.5*SP scaling. The HoT is similarly off, giving us ~6% SP scaling rather than 4.5%. And the base values are a little lower than the tooltip predicts:

No problem. I think the next couple we should focus on are EF and Holy Prism, since our data sets for those two abilities are ambiguous so far. I'd add WoG to that list, but we know it's getting buffed soon anyway, so we can probably just wait on that.

The more the better. But I think that at this point, we already trust the tooltip, so we're just confirming that our data is in the right ballpark. I'd say do ~10 casts in a couple gear sets (naked, #7, and one or two in-between). You could take CS/EF data at the same time.

The direct heal still interacts with BoG (or did, at any rate). The HoT does not (or should not, according to blue posts).

Either way, the point of testing it is to determine whether it's of any use to us. Gather the facts, and then come to a conclusion based on those facts, rather than come to a conclusion and decide to skip the facts as a result.